Regrowing Limbs: Can People Regenerate Body Parts?

Progress on the road to regenerating major body parts, salamander-style, could transform the treatment of amputations and major wounds

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Rebuilding Limbs

Most human tissues are individually able to regenerate, which suggests that regrowing complex body parts is a realistic goal. Regenerating whole limbs will require changing the signals cells receive in the wound environment so that brakes on regrowth are removed and our innate limb-building programs are reactivated.....[
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Rebuilding Limbs

Most human tissues are individually able to regenerate, which suggests that regrowing complex body parts is a realistic goal. Regenerating whole limbs will require changing the signals cells receive in the wound environment so that brakes on regrowth are removed and our innate limb-building programs are reactivated.[
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JIM WATSON AFP/Getty Images (amputee)

Blocking fibrosis

Fibroblast cells (inset) that form scar tissue at a wound site also cause organ-scarring diseases, such as pulmonary fibrosis, which constricts breathing. Learning to prevent scarring in amputation wounds as a prelude to regeneration should also yield treatments for unwanted fibrosis in other body tissues.....[
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Blocking fibrosis

Fibroblast cells (inset) that form scar tissue at a wound site also cause organ-scarring diseases, such as pulmonary fibrosis, which constricts breathing. Learning to prevent scarring in amputation wounds as a prelude to regeneration should also yield treatments for unwanted fibrosis in other body tissues.[
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Photo Researchers, Inc. (x-ray);

Human Potential

Natural human regeneration of amputated fingertips has been well documented, including the recent case of Lee Spievak. His middle finger, about an inch of which was severed by a model airplane propeller, is shown after complete healing.....[
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Human Potential

Natural human regeneration of amputated fingertips has been well documented, including the recent case of Lee Spievak. His middle finger, about an inch of which was severed by a model airplane propeller, is shown after complete healing. The injury was treated with a protein powder that might have aided regeneration by acting as a scaffold for regrowing tissues.[
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AL BEHRMAN AP Photo (Spievak);

Mammalian Digit Tip

New bone (red stain) growing from the site where a mouses digit tip was amputated (green stain) illustrates the regenerative potential present in mammals. The authors have also shown that a blastema forms at the site where a mouse digit will regenerate.....[
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Mammalian Digit Tip

New bone (red stain) growing from the site where a mouses digit tip was amputated (green stain) illustrates the regenerative potential present in mammals. The authors have also shown that a blastema forms at the site where a mouse digit will regenerate.[
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LIVING ART ENTERPRISES, LLC

Nonregenerating Vertebrate

A normal ankle and foot grew from the "elbow" of
a chicken embryo's wing after leg tissue
was grafted into the wing bud earlier in the chick's development. Regrowth of the amputated leg segment
in an animal that does not naturally regenerate shows
that limb-building programs can be reactivated when the wound environment is permissive.....[
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Nonregenerating Vertebrate

A normal ankle and foot grew from the "elbow" of
a chicken embryo's wing after leg tissue
was grafted into the wing bud earlier in the chick's development. Regrowth of the amputated leg segment
in an animal that does not naturally regenerate shows
that limb-building programs can be reactivated when the wound environment is permissive.[
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Ken Muneoka

Redirected Wound Healing

Causing a new limb to grow from the site of an incision on front of the leg of an axolotl established the basic requirements in salamanders for triggering a limb-regeneration response where normally only simple wound healing would occur.....[
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Redirected Wound Healing

Causing a new limb to grow from the site of an incision on front of the leg of an axolotl established the basic requirements in salamanders for triggering a limb-regeneration response where normally only simple wound healing would occur.[
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David M. Gardiner

The Road to Regeneration

Taking a step-by-step approach toward the goal of regrowing human limbs, scientists are learning how to control the process in natural regenerators, such as the salamander, and how to trigger similar mechanisms in animals that do not normally regrow large body parts.....[
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The Road to Regeneration

Taking a step-by-step approach toward the goal of regrowing human limbs, scientists are learning how to control the process in natural regenerators, such as the salamander, and how to trigger similar mechanisms in animals that do not normally regrow large body parts. Tapping the regenerative potential in humans will most likely involve redirecting our wound-healing responses away from scar formation in favor of
a limb-building program similar to the biological instructions that first create our limbs during fetal development.[
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Aaron Goodman

Fleshing Out

As its internal anatomy and outline become more mature, the limb lengthens to fill in the missing segment between the original amputation plane and the toes.....[
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Fleshing Out

As its internal anatomy and outline become more mature, the limb lengthens to fill in the missing segment between the original amputation plane and the toes.[
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Alice Y. Chen

Taking Shape

As the blastema grows, it begins to form the outline of the new limb, including the tip that will become the foot. The embryonic cells give rise to new tissues by proliferating and differentiating into bone, muscle, fibroblasts, and so on.....[
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Taking Shape

As the blastema grows, it begins to form the outline of the new limb, including the tip that will become the foot. The embryonic cells give rise to new tissues by proliferating and differentiating into bone, muscle, fibroblasts, and so on.[
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Alice Y. Chen

Return to the Womb

Cells that migrated to the wound revert to a less specialized embryonic state and begin dividing to populate the bud of a new limb, called a blastema.....[
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Return to the Womb

Cells that migrated to the wound revert to a less specialized embryonic state and begin dividing to populate the bud of a new limb, called a blastema.[
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Alice Y. Chen

Healing Signals

Epidermal cells form a ridge known as an apical epithelial cap, which generates critical signals that guide the behavior of other cells. Fibroblasts and muscle cells start migrating toward the wound site.....[
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Healing Signals

Epidermal cells form a ridge known as an apical epithelial cap, which generates critical signals that guide the behavior of other cells. Fibroblasts and muscle cells start migrating toward the wound site.[
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Alice Y. Chen

Wound Closure

Within hours of a leg amputation, epidermal skin cells migrate across the wound to seal it, forming a wound epidermis.....[
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Wound Closure

Within hours of a leg amputation, epidermal skin cells migrate across the wound to seal it, forming a wound epidermis.[
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Alice Y. Chen

Perfect Regeneration

Salamanders are the only vertebrates able to regrow lost limbs, as well as many other body parts, throughout their lifetimes--and they can do it repeatedly. Studies of how a limb forms on the salamander have revealed that the process begins with rapid wound closure and a rush of cells from stump tissues to the amputation site.....[
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Perfect Regeneration

Salamanders are the only vertebrates able to regrow lost limbs, as well as many other body parts, throughout their lifetimes--and they can do it repeatedly. Studies of how a limb forms on the salamander have revealed that the process begins with rapid wound closure and a rush of cells from stump tissues to the amputation site. The next stages involve reversion of those cells to an embryonic state and their building of a new limb following the same steps as in embryonic development.[
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Lisa Apfelbacher

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